The spiraling costs of plastic materials through ever increasing cost of petroleum products has necessitated reclamation of polyethylene and polypropylene scrap of all kinds which may be reused for numerous products that do not require the virgin material. The ever increasing demand for polyethylene and polypropylene products of various types may be reduced in cost substantially by using recycled materials which have been carefully controlled.
Various types of extruders which include screen changers, cleanable filters, thermal treatment of plastic materials as well as apparatus for recovering scraps of thermoplastic materials are disclosed in the prior art which include U.S. Pat. Nos. 3,480,997; 3,583,453; 3,653,419; 3,675,934; 3,962,092; 4,025,434; 4,167,384; 4,170,446; 4,189,291; and 4,257,901, among others.